Abstract
Intermediate-mass black holes (IMBHs) are the missing link between stellar-mass and supermassive black holes, widely believed to reside in at least some dense star clusters, but not yet observed directly. Tidal disruptions of white dwarfs (WDs) are luminous only for black holes less massive than ~105M⊙, therefore providing a unique smoking gun that could finally prove the existence of IMBHs beyond any reasonable doubt. Here, we investigate the tidal captures of WDs by IMBHs in dense star clusters, and estimate upper limits to the capture rates of ~1Myr−1 for galactic nuclei and ~0.01 Myr−1 for globular clusters. Following the capture, the WD inspirals onto the IMBH, producing gravitational waves detectable out to ~100Mpc by LISA for ~104M⊙ IMBHs. The subsequent tidal stripping/disruption of the WD can also release bright X-ray and gamma-ray emission with luminosities of at least ≳1040 erg s−1, detectable by Chandra, Swift, and upcoming telescopes, such as the Einstein Probe.
| Original language | English (US) |
|---|---|
| Article number | 141 |
| Journal | Astronomical Journal |
| Volume | 953 |
| Issue number | 2 |
| DOIs | |
| State | Published - Aug 20 2023 |
Funding
We thank Fred Rasio, Kyle Kremer, Chris Matzner, and the anonymous referee for helpful discussions and comments. This work was supported by NSF Grant AST-2108624 at Northwestern University, and by the Natural Sciences and Engineering Research Council of Canada (NSERC) DIS-2022-568580. G.F. acknowledges support from NASA Grant 80NSSC21K1722. R.P. acknowledges support by NSF award AST-2006839. This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. We thank Fred Rasio, Kyle Kremer, Chris Matzner, and the anonymous referee for helpful discussions and comments. This work was supported by NSF GrantAST-2108624 at North-western University, and by the Natural Sciences and Engineering Research Council of Canada (NSERC) DIS-2022-568580. G.F. acknowledges support from NASA Grant 80NSSC21K1722. R.P. acknowledges support by NSF award AST-2006839. This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science